Upland Cultivars Research Articles

Very fine roots differ among switchgrass (Panicum virgatum L.) cultivars and differentially affect soil pores and carbon processes

Switchgrass (Panicum virgatum L.) is a promising feedstock for biofuel production, with diverse cultivars representing several ecotypes adapted to different environmental conditions within the contiguous USA. Multiple field studies have demonstrated that monoculture switchgrass cultivation leads to slow to negligible soil carbon (C) gains, an outcome unexpected for such a deep-rooted perennial. We hypothesize that different switchgrass cultivars have disparate impacts on soil C gains, and one of the reasons is variations in physical characteristics of their roots, where roots directly and indirectly influence formation of soil pores. We tested this hypothesis at Great Lakes Bioenergy Research Center's research site in Michigan using two lowland cultivars (Alamo and Kanlow) and four upland cultivars (Southlow, Cave-in-Rock, Blackwell, and Trailblazer). Three types of soil samples were collected: 20 cm diameter (Ø) intact cores used for root analyses; 5 cm Ø intact cores subjected to X-ray computed tomography scanning used for pore characterization; and disturbed soil samples used for microbial biomass C (MBC) and soil C measurements. Path analysis was used to explore interactive relationships among roots, soil pores, and their impact on MBC, and ultimately, on soil C contents across six cultivars. The abundance of very fine roots (<200 μm Ø) was positively associated with fractions of pores in the same size range, but negatively with distances to pores and particulate organic matter. Higher abundance of such roots also led to greater MBC, while greater volumes of medium pores (50–200 μm Ø) and shorter distances to pores increased MBC. Results suggest that the greater proportion of very fine roots is a trait that can potentially stimulate soil C gains, with pore characteristics serving as links for the relationship between such roots and C gains. However, at present, ten years of cultivation generated no differences in soil C among the studied cultivars.

Evaluation Methods, Resistant Germplasm, and Breeding for Resistance to Bacterial Blight in Cotton: A Review

Bacterial blight (BB) caused by Xanthomonas citri pv. malvacearum (Xcm) is an important cotton (Gossypium spp.) production problem. In the U.S., BB has been controlled effectively using resistant cultivars and acid-delinted seed since the 1970s; however, resurgence of BB occurred in the early 2010s because of negligence in breeding. This review provides an up-to-date account on the pathogen, resistance evaluation methods, resistant germplasm lines, and breeding methods. Twenty-two Xcm races have been reported worldwide, and race 18 is currently the only one found in production fields in the U.S. To evaluate cotton for BB resistance, a pressure-sprayer-based method with surfactant in the field and a cotyledon-scratching-based method in the greenhouse are most often used. Breeding for BB resistance was highly successful in Sudan between the late 1930s and 1960s, when many resistance genes were transferred to G. barbadense from G. arboreum, G. herbaceum, G. anomalum, and G. hirsutum. Breeding for BB resistance commenced in the U.S. in the 1940s, leading to development of numerous resistant Upland cultivars. Although backcrossing was often used to transfer resistance genes in early years, forward breeding has been the breeding method of choice. Currently, some and possibly all resistant cultivars in the U.S. possess the resistance gene B12, which confers immunity with no water-soaked symptoms. Although B12-based resistance has held for a long time, identification of new resistant sources is needed to prevent an epidemic of BB due to evolution or introduction of possible new virulent Xcm races.

Cotton Fiber Strength Measurement and Its Relation to Structural Properties from Fourier Transform Infrared Spectroscopic Characterization

There has been an interest in understanding the relationship between textile cotton fiber strength (or tenacity) and structure for better fiber quality measurement and enhancement. This study utilized coupled Stelometer and high volume instrument (HVI) measurements with attenuated total reflection Fourier transform infrared spectroscopy methods to relate fiber strength and associated properties (Stelometer elongation and HVI micronaire) with structure properties on six Upland (as A, B, C, D, E, and F) and one Pima cultivar. Although Stelometer tenacity agreed with HVI strength in general, the Upland D cultivar (immature) was observed to show the lowest HVI strength value, while the Upland F cultivar (larger infrared crystallinity index) was found to possess the smallest Stelometer tenacity value. A few strong and significant correlations were noted, for example, between infrared crystallinity and Stelometer elongation for the Upland A fibers, between infrared maturity and Stelometer tenacity for the Upland C fibers, and between infrared maturity and HVI strength for the Upland D fibers. Furthermore, there were apparent distinctions in regressions and statistics of examined correlations between each Upland cultivar and their combined fiber set, addressing the challenge of understanding the unique response between fiber physical and structure properties from different measurements even within one cotton cultivar.

BRS A504 CL: a new herbicide resistant upland cultivar with high quality grain

BRS A504 CL: a new herbicide resistant upland cultivar with high quality grain

Varietal Differences in the Root Systems of Rice (Oryza sativa L.) under Drip Irrigation with Plastic Film Mulch

With the escalating water scarcity in agriculture, a novel water-saving technique has emerged: drip irrigation with plastic film mulch (DI). Root function is crucial for sustaining rice production, and understanding its response to DI is essential. However, few studies have evaluated root systems in rice varietals and examined which kind of root system contributes to improving rice grain yield and water productivity in DI. If varietal differences of root reactions for water regimes were made clear, it might be more effective to find suitable varieties for DI and to improve grain yield in the DI system. To fill this knowledge gap, we conducted a two-year field experiment comparing two irrigation systems: continuous flooding (CF) and DI. We analyzed their effectiveness with four rice cultivars, including upland, F1 lowland, animal feed lowland, and lowland cultivars. Vertical root distribution, root bleeding rate, photosynthetic-associated parameters, water productivity, and yield performance were analyzed. In our study, the average grain yield of cultivars in the DI system (6.4 t/ha) was equivalent to those in the CF system (6.6 t/ha). The average water productivity under DI (0.34–0.75 kg m−3) demonstrated significant water-saving potential, saving approximately 35% of the total water supplied, resulting in higher water productivity compared to CF (0.27–0.51 kg m−3). Among the cultivars, the deep root weight of the upland cultivar significantly increased by 51% under DI compared to CF. The deep root ratio was positively correlated with the transpiration rate, grain yield, and water productivity, suggesting its contribution to high transpiration, thus maintaining a high carbon assimilation rate that results in high yield and water productivity. Therefore, deep roots are a notable trait corresponding to high yield under DI, and should be considered for the development of rice growth models for DI and the breeding of aerobic-adapted cultivars.

Ethnolinguistic associations and genetic diversity of rice landraces in Nagaland, India

Societal Impact StatementPreserving and conserving crop landraces, tended by indigenous farming communities, is crucial for future food security. This research focused on rice landrace diversity in the north‐eastern Himalayan region of Nagaland, India, where Naga communities cultivate rice according to their dietary and cultural preferences. Rice diversity is closely linked to the region's ethnolinguistic and ecological variety. On‐farm conservation, in collaboration with indigenous communities, is imperative to protect these germplasm resources. Involving these communities actively in conservation efforts will safeguard their traditional knowledge, endorse sustainable farming practices, and enhance the resilience of local agricultural systems.Summary Understanding the genetic diversity and cultural significance of crop landraces is crucial for their conservation and sustainable utilization. This study focused on rice landraces from Nagaland in north‐eastern India to assess their genetic diversity and explore their associations with ethnolinguistic groups. We collected 78 rice landraces from Nagaland and a small part of Manipur and conducted microsatellite genotyping for genetic analysis. We integrated social anthropology and population genetics analyses of rice landraces to glean insights into the genetic diversity, population structure, and ethnolinguistic history of rice cultivation in Nagaland. The study revealed the rich cultural significance of rice landraces among the Nagas. Farmers practiced small‐scale subsistence farming, maintaining diverse rice landraces. Naming conventions were based on factors such as seed source, color, grain type, and ecological suitability. Rice landraces played important roles in ethnic cultures, festivals, and religious ceremonies. Genetic analysis identified significant diversity, with 277 alleles across 69 loci and a moderate gene diversity of 0.57. Two distinct sub‐populations were identified, with one dominated by Chakhesang and Angami Nagas and the other by Sümi and Lotha accessions. Differentiation was observed between lowland and upland cultivars, with one sub‐population comprising exclusively lowland varieties. Cultural factors and cultivation practices influenced population differentiation, with ethnicity and ecotype having a significant impact. The study also highlighted the correlation between ethnolinguistic differentiation and the indica–japonica structuring of rice landraces. Different ethnic groups in Nagaland had distinct cultivation practices, contributing to genetic differentiation. Overall, this research emphasizes the need to preserve rice landraces and associated traditional knowledge for future improvements and cultural heritage conservation. It provides insights into genetic diversity, cultural significance, and the relationship between genetic diversity, cultural practices, and agricultural traditions.

Seed Hull Fracture Resistance of Upland and Pima Cotton Cultivars

Seed durability is a current issue of cotton ginners, who have noted smaller and weaker seed, lower seed grades, and increased seed coat fragments within ginned cotton fiber. To better understand the differences in the seed hull properties of Upland (Gossypium hirsutum L.) and Pima (G. barbadense L) seed, compression testing was conducted to determine the seed hull fracture resistance of both species. Plants were grown in Five Points, CA, U.S., for two years. After roller ginning, seed were conditioned to standard environmental conditions and were compressed until rupture on a material strength tester. Seed of the Pima cultivars generally required greater maximum compressive force and energy to rupture than did the seed of the Upland cultivars. However, when the seed were compressed in a vertical orientation, a few individual Upland cultivars did have compression properties within the range of values observed for the Pima cultivars. Hence, it is possible to find Upland seed with compression properties comparable to or slightly greater than those of some Pima seed. Differences in the data for the two years showed that growing environment affects seed hull strength properties. The results should help clarify some conflicting literature regarding the relative strength attributes of Gossypium species seed.

Divergent Metabolic Changes in Rhizomes of Lowland and Upland Switchgrass (Panicum virgatum) from Early Season through Dormancy Onset.

High-biomass-yielding southerly adapted switchgrasses (Panicum virgatum L.) frequently suffer from unpredictable winter hardiness at more northerly sites arising from damage to rhizomes that prevent effective spring regrowth. Previously, changes occurring over the growing season in rhizomes sampled from a cold-adapted tetraploid upland cultivar, Summer, demonstrated a role for abscisic acid (ABA), starch accumulation, and transcriptional reprogramming as drivers of dormancy onset and potential keys to rhizome health during winter dormancy. Here, rhizome metabolism of a high-yielding southerly adapted tetraploid switchgrass cultivar, Kanlow-which is a significant source of genetics for yield improvement-was studied over a growing season at a northern site. Metabolite levels and transcript abundances were combined to develop physiological profiles accompanying greening through the onset of dormancy in Kanlow rhizomes. Next, comparisons of the data to rhizome metabolism occurring in the adapted upland cultivar Summer were performed. These data revealed both similarities as well as numerous differences in rhizome metabolism that were indicative of physiological adaptations unique to each cultivar. Similarities included elevated ABA levels and accumulation of starch in rhizomes during dormancy onset. Notable differences were observed in the accumulation of specific metabolites, the expression of genes encoding transcription factors, and several enzymes linked to primary metabolism.

Traces of Introgression from cAus into Tropical Japonica Observed in African Upland Rice Varieties

BackgroundAsian rice Oryza sativa, first domesticated in East Asia, has considerable success in African fields. When and where this introduction occurred is unclear. Rice varieties of Asian origin may have evolved locally during and after migration to Africa, resulting in unique adaptations, particularly in relation to upland cultivation as frequently practiced in Africa.MethodsWe investigated the genetic differentiation between Asian and African varieties using the 3000 Rice Genomes SNP dataset. African upland cultivars were first characterized using principal component analysis among 292 tropical Japonica accessions from Africa and Asia. The particularities of African accessions were then explored using two inference techniques, PCA-KDE for supervised classification and chromosome painting, and ELAI for individual allelic dosage monitoring.Key ResultsAmbiguities of local differentiation between Japonica and other groups pointed at genomic segments that potentially resulted from genetic exchange. Those specific to West African upland accessions were concentrated on chromosome 6 and featured several cAus introgression signals, including a large one between 17.9 and 21.7 Mb. We found iHS statistics in support of positive selection in this region and we provide a list of candidate genes enriched in GO terms that have regulatory functions involved in stress responses that could have facilitated adaptation to harsh upland growing conditions.

Deepwater response in the African cultivated rice Oryza glaberrima

ABSTRACT Partial submergence of Oryza sativa deepwater rice elicits enhancement of internodal elongation, referred to as deepwater response, conferred by three types of genes, SNORKEL1/2 (SK1/2), SEMIDWARF1 (SD1), and ACCELERATOR OF INTERNODE ELONGATION 1 (ACE1). We investigated the presence and expression of these genes in the African cultivated rice Oryza glaberrima and the relationship between these genes and the deepwater response of O. glaberrima. In 49 of the 50 accessions tested, one or two SK genes were identified, which could be divided into three types of SK1 and four types of SK2. The accessions with the SK2 type whose expression was induced by submergence demonstrated rapid internodal elongation under submergence. In most of these accessions, submergence also increased the expression of SD1 and ACE1 genes. However, the accessions did not possess the haplotype of SD1 that is associated with high deepwater response in O. sativa. In contrast, they possessed the type of ACE1 gene similar to that in O. sativa deepwater rice. These results indicate that the molecular mechanisms underlying induction of deepwater response in O. glaberrima are similar to that found in deepwater rice of O. sativa and suggest that most O. glaberrima cultivars, including upland cultivars, can exhibit rapid internodal elongation under submergence.

Identifying genes associated with abiotic stress tolerance suitable for CRISPR/Cas9 editing in upland rice cultivars adapted to acid soils.

Five genes of large phenotypic effect known to confer abiotic stress tolerance in rice were selected to characterize allelic variation in commercial Colombian tropical japonica upland rice cultivars adapted to drought-prone acid soil environments (cv. Llanura11 and Porvenir12). Allelic variants of the genes ART1, DRO1, SUB1A, PSTOL1, and SPDT were characterized by PCR and/or Sanger sequencing in the two upland cultivars and compared with the Nipponbare and other reference genomes. Two genes were identified as possible targets for gene editing: SUB1A (Submergence 1A), to improve tolerance to flooding, and SPDT (SULTR3;4) (SULTR-like Phosphorus Distribution Transporter), to improve phosphorus utilization efficiency and grain quality. Based on technical and regulatory considerations, SPDT was targeted for editing. The two upland cultivars were shown to carry the SPDT wild-type (nondesirable) allele based on sequencing, RNA expression, and phenotypic evaluations under hydroponic and greenhouse conditions. A gene deletion was designed using the CRISPR/Cas9 system, and specialized reagents were developed for SPDT editing, including vectors targeting the gene and a protoplast transfection transient assay. The desired edits were confirmed in protoplasts and serve as the basis for ongoing plant transformation experiments aiming to improve the P-use efficiency of upland rice grown in acidic soils.

Lignin and cellulose content differences in roots of different cotton cultivars associated with different levels of Fusarium wilt race 4 (FOV4) resistance-response

Fusarium wilt disease is caused by fungal pathogen Fusarium oxysporum f. sp. v asinfectum (FOV) race 4 (FOV4), which enters the plant through the root system for its successful colonization of xylem. Plant cell wall forms the primary barrier against pathogen infection in addition to providing the mechanical support. However, the role of cell walls for developing FOV4 resistance has not been explored. The present study focused on examining the variation in lignin and cellulose contents in root tissue of Pima ( Gossypium barbadense L.) and Upland ( G. hirsutum L.) cotton with different levels of FOV4 wilt resistance-response. Traditional cultivar-checks susceptible Pima S-7, resistant Pima S-6, susceptible Upland Stoneville 474, and resistant Upland PSSJ-FRU14 (U77B) were used in the present study. Biochemical differences in root cell walls were investigated first by a rapid visual staining method for both lignin (phloroglucinol-HCL) and cellulose (Congo red) contents of root cross sections at three stages of cotton plant development followed by biochemical estimation of root lignin and cellulose contents. These studies revealed differences between susceptible and resistant cultivars at specific stages visually by rapid staining as well as biochemically in their cellulose and lignin contents within Pima and Upland cultivars. This is the first report in lignin and cellulose content estimation of Pima and Upland resistant and susceptible FOV4 cotton cultivars and paves the way for developing cell wall mediated FOV resistance. • FOV4 causes cotton wilt disease and causes enormous yield losses. • Cell wall acts as a physical and biochemical barrier against pathogen infection. • We hypothesize that cell wall plays a major role in in FOV4 resistance. • Histochemical analysis showed higher root cellulose and lignin in resistant lines. • Resistant lines showed higher root cellulose and lignin contents.

Registration of 17 upland cotton germplasm lines with improved resistance to Fusarium wilt race 4 and good fiber quality

AbstractWith Fusarium wilt (Fusarium oxysporum f. sp. vasinfectum W.C. Snyder &amp; H.N. Hansen) race 4 (FOV4) formally identified in proximity to the High Plains of west Texas—the largest upland cotton (Gossypium hirsutum L.) producing region in the United States—the need to develop cultivars resistant to FOV4 has become urgent. Currently, there are no commercial upland cultivars available claiming FOV4 resistance. Fusarium wilt race 4, a soil‐borne fungus, has affected the cotton crop in the San Joaquin Valley of California for two decades. The primary purpose for the release of the upland PSSJ‐FRU01–PSSJ‐FRU17 (Reg. no. GP‐110–GP‐1126, PI 699966–PI 699982) germplasm lines is to provide cotton breeders with urgently needed sources for FOV4 resistance in upland cotton. The lines were derived from six different cross‐combinations using 10 parental lines with different genetic backgrounds (e.g., ‘DES 920’ [PI 536522], ‘NM12Y1004’ [NuMex COT 15 GLS, PI 678371], ‘MARS ROSE CLUSTER’ [PI 528483], ‘AUBURN M’ [PI 529214], and ‘SA‐3208’ [LIAO MIAN 7 HAO]). Several cycles of selection were applied to these developed lines based on an asymptomatic single plant selection after greenhouse FOV4 inoculations or infested field evaluations from F1 to F4. In 2019–2021 evaluations, germplasm lines showed enhanced resistance to FOV4 with significantly lower percentage mortality and vascular root staining as compared to resistant controls (‘Pima‐S6’ and ‘PHY 881 RF’) and improved fiber strength and some long fibers. These released lines will help to reduce the vulnerability of upland cotton to this fungal pathogen and advance efforts to broaden the resistance genetic base which is critical for the upland cotton industry.

Growth, boll development, agronomic performance, and fiber quality of Gossypium barbadense L. in the southeastern U.S. Coastal Plain

AbstractPima (Gossypium barbadense L.) cotton is currently grown commercially in the western United States and has exceptional fiber quality, which provides an economic value almost two times greater than Upland (Gossypium hirsutum L.) cotton. Due to limited experience with Pima production in the southeastern United States, our primary objective was to compare the growth, development, agronomic performance, and fiber quality of four Pima genotypes with a high‐yielding high fiber quality commercial Upland cultivar under irrigated and dryland conditions at different planting dates. Lint yields of all Pima genotypes were ∼50% less and had lower lint percentages (38.0–42.4%) than the Upland genotype (45.7%); however, the Pima genotypes had consistently lower micronaire values and increased fiber strength, length, and uniformity. Although irrigation did not significantly impact agronomic and fiber quality performance, plants grown under supplemental irrigation developed 10% more bolls throughout the season, mostly occurring on monopodial branches and at mainstem nodal positions above 15. Bolls on Pima genotypes were 13–34% smaller than the Upland genotype and developed at more distal and higher nodal positions in the plant canopy. The highest net returns were found in 2019 at the early planting date, displaying the importance of timely planting of Pima genotypes when grown in the southeastern United States. Results suggest that irrigation may not be required for Pima production in the southeast, early planting is preferred to obtain maximum yields, and increasing lint percent, boll number, or earliness through breeding may improve Pima yields in the southeastern United States.

Key environmental and production factors for understanding variation in switchgrass chemical attributes

AbstractSwitchgrass (Panicum virgatum L.) is a promising feedstock for bioenergy and bioproducts; however, its inherent variability in chemical attributes creates challenges for uniform conversion efficiencies and product quality. It is necessary to understand the range of variation and factors (i.e., field management, environmental) influencing chemical attributes for process improvement and risk assessment. The objectives of this study were to (1) examine the impact of nitrogen fertilizer application rate, year, and location on switchgrass chemical attributes, (2) examine the relationships among chemical attributes, weather and soil data, and (3) develop models to predict chemical attributes using environmental factors. Switchgrass samples from a field study spanning four locations including upland cultivars, one location including a lowland cultivar, and between three and six harvest years were assessed for glucan, xylan, lignin, volatiles, carbon, nitrogen, and ash concentrations. Using variance estimation, location/cultivar, nitrogen application rate, and year explained 65%–96% of the variation for switchgrass chemical attributes. Location/cultivar × year interaction was a significant factor for all chemical attributes indicating environmental‐based influences. Nitrogen rate was less influential. Production variables and environmental conditions occurring during the switchgrass field trials were used to successfully predict chemical attributes using linear regression models. Upland switchgrass results highlight the complexity in plant responses to growing conditions because all production and environmental variables had strong relationships with one or more chemical attributes. Lowland switchgrass was limited to observations of year‐to‐year environmental variability and nitrogen application rate. All explanatory variable categories were important for lowland switchgrass models but stand age and precipitation relationships were particularly strong. The relationships found in this study can be used to understand spatial and temporal variation in switchgrass chemical attributes. The ability to predict chemical attributes critical for conversion processes in a geospatial/temporal manner would provide state‐of‐the‐art knowledge for risk assessment in the bioenergy and bioproducts industry.

Profiling of Water-Use Efficiency in Switchgrass (Panicum virgatum L.) and the Relationship with Cadmium Accumulation

Planting bioenergy crops with high water-use efficiency (WUE) on heavy metal-polluted land is a good practice for biomass production and phytoremediation. Switchgrass (Panicum virgatum L.), a C4 perennial bioenergy grass, is native to the United States. The relationship between the WUE and Cd accumulation of switchgrass has seldom been studied. Here, the WUE and Cd accumulation characteristics of 14 high-biomass switchgrass cultivars were investigated under Cd stress by hydroponic culture. The main results showed that Cd inhibited the instantaneous WUE in switchgrass seedlings and that the inhibition rate was more significant in the upland types than in the lowland types of switchgrass. A positive correlation was found between relative WUE and Cd accumulation in roots and shoots. The relative expression level of stomatal control-related genes (ERECTA and EPF1) in lowland cultivars with high WUE was higher than in upland cultivars with low WUE, both in control and Cd treatment conditions. The results suggest that it would be possible to further select and cultivate switchgrass with high WUE and a high capacity for Cd accumulation for phytoremediation in Cd-contaminated land.

Genetic Transformation of Recalcitrant Upland Switchgrass Using Morphogenic Genes.

Switchgrass (Panicum virgatum) is an excellent feedstock for biofuel production. While genetic transformation is routinely done in lowland switchgrass, upland cultivars remain recalcitrant to genetic transformation. Here we report the establishment of an efficient and reproducible transformation protocol for two upland cultivars, ‘Summer’ and ‘Blackwell’, by ectopic overexpression of morphogenic genes, Baby boom (Bbm) and Wuschel2 (Wus2). Two auxotrophic Agrobacterium strains, LBA4404Thy- and EHA105Thy-, each harboring the same construct containing ZmBbm, ZmWus2, and a green fluorescence protein (GFP) gene, ZsGreen1, were used to infect immature leaf segments derived from in vitro grown seedlings. The Agrobacterium strains also contain a transformation helper plasmid that carry additional copies of Agrobacterium virulence genes. GFP-expressing calli were identified and selected for regeneration. The highest transformation efficiency of 6% was obtained for the tetraploid cultivar Summer when LBA4404Thy- was used for infection, which is twice of that for the octoploid cultivar Blackwell. LBA4404Thy- consistently outperformed EHA105Thy- on transformation frequency across the two cultivars. Fifteen randomly selected putative transgenic plants of Summer and Blackwell, representing independent callus events, were confirmed as transgenic by the presence of the transgene, ZmAls, and the absence of AtuFtsZ, a chromosomal gene specific to the Agrobacterium strain LBA4404 using polymerase chain reaction. Transgene integration and expression was further confirmed by the detection of GFP in roots, and the resistance to herbicide injury to leaves of selected putative transgenic plants. The ZmBbm and ZmWus2 genes were successfully removed from 40 to 33.3% of the transgenic plants of Summer and Blackwell, respectively, via the Cre-Lox recombination system upon heat treatment of GFP-expressing embryogenic calli. Our successful transformation of recalcitrant upland switchgrass provides a method for gene function analysis and germplasm enhancement via biotechnology.

Variability, heritability, and performance of 28 West Sumatran upland rice cultivars, Indonesia

Abstract. Marwan AP, Munandar A, Anwar A, Syarif A, Hayati PKD. 2022. Variability, heritability, and performance of 28 West Sumatran upland rice cultivars, Indonesia. Biodiversitas 23: 1058-1064. The abundance of genetic diversity, especially local upland rice cultivars, makes an excellent opportunity to obtain local cultivars with the desirable character. The study aimed to assess the genetic variability and heritability of agronomic traits among local upland rice cultivars from West Sumatra. In this study, 28 local upland cultivars from West Sumatra were subjected to the analysis of variance. The research was conducted from November 2020 to April 2021 at the Research Station of the Faculty of Agriculture, Andalas University, Padang. The evaluation was conducted using a Randomized Complete Block Design with three replicates. Results showed variation in each agronomic trait, ranging from intermediate to tall in plant height, short to moderate in panicle length, low to moderate in the number of tillers, days to flowering and days to maturity, and light to moderate in grain yield. Plant height, number of tillers, days to flowering, and days to maturity were traits with high to moderately high GCV values and high heritability values. The number of tillers and days to maturity could be chosen as selection criteria for assembling superior varieties. Both traits performed high heritability estimates and significant genotypic correlation with grain yield.

Genetics and Breeding for Glandless Upland Cotton With Improved Yield Potential and Disease Resistance: A Review.

Glandless cotton (devoid of toxic gossypol) can be grown as a triple-purpose crop for fiber, feeds, and food (as an oil and protein source). However, its sensitivity to insect pests and its low yield due to the lack of breeding activities has prevented the realization of its potential in commercial seed production and utilization. Since the mid-1990s, the commercialization of bollworm and budworm resistant Bt cotton and the eradication of boll weevils and pink bollworms have provided an opportunity to revitalize glandless cotton production in the United States. The objectives of this study were to review the current status of genetics and breeding for glandless cotton, with a focus on the progress in breeding for glandless Upland cotton in New Mexico, United States. Because there existed a 10–20% yield gap between the best existing glandless germplasm and commercial Upland cultivars, the breeding of glandless Upland cultivars with improved yield and disease resistance was initiated at the New Mexico State University more than a decade ago. As a result, three glandless Upland cultivars, i.e., long-staple Acala 1517-18 GLS, medium staple NuMex COT 15 GLS, and NuMex COT 17 GLS with Fusarium wilt race 4 resistance were released. However, to compete with the current commercial glanded cotton, more breeding efforts are urgently needed to introduce different glandless traits (natural mutations, transgenic or genome-editing) into elite cotton backgrounds with high yields and desirable fiber quality.

Tolerance of Pima and Upland cotton to trifloxysulfuron (Envoke) herbicide under field conditions

Trifloxysulfuron (Envoke) is an acetolactate synthase-inhibitor herbicide and can be used to control many broadleaf weeds and nutsedges in cotton production. However, there is a lack of information on genotypic variation in response to the herbicide. In this field study, 60 Pima (Gossypium barbadense L.) lines, 122 Upland (G. hirsutum L.) lines, and 9 Upland × Pima segregating populations were divided into five tests (18A, 18B, 18G, 18RB, and 18HQ) to evaluate trifloxysulfuron tolerance at the 7-true leaf stage (42 days after planting) under the same field conditions in 2018. Across the five tests, Pima cotton genotypes tested in this study did not show any visual crop injury based on percentage of plants with chlorosis at 6 days after treatment (DAT), indicating consistent and high levels of trifloxysulfuron tolerance. However, the response to trifloxysulfuron within Upland cotton is highly variable. While Upland cotton is overall more sensitive to trifloxysulfuron with crop injury up to 80% than Pima cotton, 19 lines had injury below 5% including one line with no visual injury, and 19 lines had injury between 5% and 10%. In test 18HQ with 15 transgenic Upland cultivars and 17 non-transgenic Upland lines, the analysis of variance detected a significant genotypic difference. The broad-sense heritability estimates for trifloxysulfuron tolerance based on crop injury at 6 DAT was 0.555, suggesting that trifloxysulfuron tolerance in Upland cotton is moderately heritable. This study represents the first report that Pima cotton and many Upland cotton lines are highly tolerant to trifloxysulfuron with no or little crop injury.